Tires for passenger vehicles usually comprise:
two beads designed to be in contact with a wheel rim, each bead comprising at least one annular reinforcing structure and a bead filler, the bead filler being located radially outside of the annular reinforcing structure;
two sidewalls extending the beads radially toward the outside, the two sidewalls joining in
a crown comprising a crown reinforcement surmounted by a tread;
at least one carcass reinforcement extending from the beads through the sidewalls to the crown, and comprising a plurality of carcass reinforcing elements. Very often the carcass reinforcement is anchored in the two beads by a turn-up around the annular reinforcing structure in such a way as to form in each bead an “incoming portion” and a “wrapped-around portion”. The bead filler is located at least partially between the incoming portion and the wrapped-around portion of the carcass reinforcement.
Document U.S. Pat. No. 5,526,863 teaches the provision of a special bead, with the object of reducing the mass of the bead and improving the rolling resistance of such a tire. The tire disclosed in that document comprises a bead filler comprising:
a first part of tapered radial section, this first part becoming progressively thinner radially toward the outside before turning into
a second part with a radial section that has an approximately constant width, the second part being located radially outside of the first part and turning into
a third part with a radial section that tapers off, the third part being situated radially outside of the second part.
The bead filler extends radially outside of the radially innermost point of the annular reinforcing structure of the bead as far as a radial distance from the said point that is greater than or equal to 30% of the radial height H of the tire.
Each bead also comprises an outer band placed axially outside of both the carcass reinforcement and the bead filler. This outer band extends radially toward the outside, from a radially inner end located at a distance less than or equal to 20% of the radial height H of the tire from the radially innermost point of the annular reinforcing structure of the bead, as far as a radially outer end, and the radial distance from the radially outer end of the outer band to the radially inner end of the outer band being greater than or equal to 40% of the radial height H of the tire.
Since that patent, the oil price rise and the awakening of consumers' ecological consciences have further increased the need to reduce tire rolling resistance, as the latter has a direct impact on fuel consumption. Thus, the reduction of rolling resistance obtained with a tire according to document U.S. Pat. No. 5,526,863 is no longer sufficient.